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Optimised Femtosecond Laser System

02 Februari 2013 129 views

The Catalys™ Precision Laser system (OptiMedica), a next generation
femtosecond laser system optimised for cataract surgery, performs
anterior capsulotomies with greater precision than that achieved
manually by experienced surgeons and all but eliminates the need for
ultrasound during lens emulsification and removal, said h Burkhard Dick
MD, PhD, Ruhr University Eye Clinic, Bochum, Germany. "The improvements
in precision made possible by the Catalys system are truly remarkable
and represent a significant advancement in the practice of modern
cataract surgery," Prof Dick said at the 16th EsCRs Winter Meeting.

He
noted that he first began working with the Catalys system in December
of last year and since that time has used it in over 140 cataract
procedures. To illustrate the potential benefits that the system can
provide to cataract surgeons and their patients, Prof Dick presented the
results achieved in 57 eyes of patients who underwent femtosecond
laser-assisted cataract surgery and compared them with those he achieved
in 52 eyes of patients who underwent standard phacoemulsification with
manually performed capsulorhexes.

The patients in both the
femtosecond laserassisted and standard phacoemulsification groups had
cataracts ranging from LOCs grade one to grade four in density. Those in
the femtosecond group had a slightly higher LOCs grade with mean
nuclear density 3.4. in all eyes in the femtosecond-laser treated group
Prof Dick used the same femtosecond laser settings in terms of laser
fragmentation pattern, pulse energy, grid spacing and spot separation.
He also used the stellaris phacoemulsification system (Bausch + Lomb)
with a coaxial technique in all eyes.

Accurate and safeProf
Dick noted that examination of the removed capsule tissue showed that
capsulotomies created with the laser deviated from their target diameter
by a mean of only 29.0 microns. That compared to a mean deviation from
target diameter of 339.0 microns in the manually created capsulorhexes.
in addition, the mean circularity of the capsulotomies, where 1.0
represents a perfect circle, was 0.936 in the femtosecond group,
compared to 0.774 in the manual group. Moreover, eyes undergoing
cataract surgery with the Catalys system required only a minimal amount
of effective phaco time in even the hardest cataracts. The mean
effective phaco time was only 0.16 seconds in 57 eyes that underwent
phaco-fragmentation with the femtosecond laser, compared to 4.07 seconds
in 52 eyes that underwent standard phacoemulsification, representing a
96 per cent reduction in phaco time.

Furthermore, the amount of
effective phaco time required in eyes with LOCs grade ii, iii, iV
cataracts was only 0.02 seconds, 0.16 seconds, and 0.25 respectively in
eyes treated with femtosecond laser. That compared to phaco time
requirements of 1.29 seconds, 1.96 seconds, and 3.32 seconds in the
conventional phacoemulsification group, respectively, for the same
grades of cataract. "The exposure to ultrasound has been minimised or
eliminated, with 74 per cent of the cases requiring 0.25 seconds or less
and 31 cases using zero seconds. The Catalys technology i believe may
enable cataract removal via aspiration through a 1.2mm incision. if
consistently demonstrated, this result will create need for new iOLs
that will fit through these incisions," he added.

In regards to
safety, Prof Dick said that there were no capsular tears or vitreous
loss or other iatrogenic complications in any eyes. Eyes treated with
Catalys had corneas that were extremely clear from the immediate
postoperative onward. Moreover, the conjunctiva remained unaltered, even
in patients receiving anticoagulant therapy due to minimal IOP rise
induced by Liquid Optics™ suction ring. in the femtosecond group,the iOL
positioning was perfect with all types of IOLs used including toric and
accommodative iOLs, he added.

Catalys: key technologiesProf
Dick noted that the Catalys Precision Laser system combines an
ultra-rapid femtosecond laser, integrated optical coherence tomography
imaging, and specific pattern scanning technology. Furthermore, the
Liquid Optics™ interface fills in corneal surface irregularities with
liquid and thereby optimises the optical path for visualisation and the
delivery of laser energy to the patient's eye, he said. "When you apply
the suction ring to the eye, the intraocular pressure rise is low. The
mean IOP increase we measured was 10 mmhg. And because it is a
fluid-filled interface, the cornea is not applanated," he noted.

The
Catalys system provides visualisation of the ocular surfaces, from the
corneal surface into the vitreous, using an integrated infrared camera
and three-dimensional spectral domain OCT imaging technology, Prof Dick
said. The system also has built in algorithms that detect and map in 3D
relevant ocular surfaces to customise treatment plan with a well-defined
safety zone. Once the surgeon has confirmed the treatment plan on the
OCT images, the treatment proceeds with the capsulotomy and
phaco-fragmentation. The capsulotomy takes a few seconds to complete and
phacofragmentation time is dependent on a number of factors such as
pattern chosen, grid spacing and pupil dilation. The entire procedure
time (from suction on to suction off at completion of cuts) had mean of
two and a half minutes, the maximum time was three and a half minutes
and the fastest was one and a half minutes.

Summarising his
experience in his first 140 cataract cases with the Catalys system, Prof
Dick said that it improved the precision of sizing the capsulotomy
compared with manual technique. The system also demonstrated a
significant improvement in precision of capsulotomy size and shape. The
use of the laser also resulted in a considerable reduction in ultrasound
energy use during phacoemulsification. "The next goal will be to
eliminate ultrasound phaco totally by modifying the instruments and the
vacuum settings and laser settings. i'm very confident that femtosecond
cataract surgery will become an integral part of our surgical options,"
he concluded.